Glossary: GHz

Gigahertz. The Hertz is the unit of frequency - it means cycles per second. 'Giga' in engineering means one thousand million - rather less than the 'giga' used to describe memory size in some computers! For the confused, the reason for the difference is that in computers binary codes are used to contact, or 'address' each stored byte of data. The number of different codes on 'addresses' that can be generated by binary numbers is calculated from two raised to the power of the number of bits in the code. So 2-bit code provides two to the power of two which equals four addresses and so on. The closest we can get to one thousand million is to use a 30-bit binary code which yields 1,073,741,824 - the 'giga' used to describe computer memory capacity.